OTA HD vs Mpeg4 HD

Discussion in 'DirecTV TiVo Powered PVRs & Receivers' started by buzzmc1, Dec 22, 2005.

  1. Jan 29, 2006 #81 of 118
    AbMagFab

    AbMagFab What happened, TiVo?

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    Yeah, DC isn't too bad. ABC, NBC, and CBS all have some goofy weather subchannel, but it seems to be relatively low bandwidth.

    Except for UPN (which is still in test mode), all 5 nets look great in this area. CBS has overall the best look and manages to screw up the least. Fox looks great, but is only 720p (which is noticable), but they also screw up very little. ABC looks great when it's working, but they have lots of transmitter problems (hiccups and such). NBC looks okay, but they seem to forget to switch to HD about 20% of the time. I don't watch much WB, but when I do, it's generally very good.

    So overall, a good set of OTA networks here.

    And I agree with one of your other posts - give me OTA HD, and I could almost live without most of the other channels. I pay for them all because I like the options, but if DirecTV keeps raising rates, and screwing the quality, I'll lower my package just to make a point, and because it's simply not worth it.
     
  2. Jan 29, 2006 #82 of 118
    TyroneShoes

    TyroneShoes HD evangelist

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    You are confusing artifacts from compression with reinterpolation. What DirecTV is doing to 1920x1080 signals is reinterpolating them to 1280x1080. Yes, that implies that they are decompressing and recompressing the signal to accomplish that, but no, it does not imply that this means that such a process will add more compression artifacts. It takes severe compression to create visible artifacts, and this is not a severe compression process.

    What you might see on a 1080p set vs. a 768 or 720 set is a difference in resolution, but only if the original source material was fully resolved at 1080p to begin with, and very little 1080i source material currently is. But any compression artifacts that might be added in DTV's process would be negligible and very likely invisible. In fact, it can be argued that a lower resolution might actually provide fewer digital artifacts because it takes fewer bits to transmit, making bit starving less likely, all else being equal, and that is the very reason DTV does this in the first place...it is a tradeoff in resolution for equivalent artifacting at a lower bandwidth.

    Assuming that because content looks worse on your 1080 set might be due to increased artifacts from DTV's reinterpolation process is just ludicrous. There are no more artifacts to see. The only difference is in the native resolution of your set and the transmitted resolution of DTV vs. OTA.

    Math hurts my brain too, but a 1920x1080 set will display the DTV image at 1280x1080, and a 768 set will display it at 1280x768, which means resolution in the H rez should appear the same on both, the difference being in the V dimension only, which is a difference in the sets, and NOT in the DTV original image as compared to OTA (1080 reinterpolated to 768 is the same for both).

    Not only that but the effective perceived vertical resolution of 1080i tops out at about 756 for all raster-scanned images due to Kell factor alone (0.7X1080), including all images shot with a camera or telecined over from film, so a 768 V rez will not really display anything visibly different than a set with 1080 capability. And you have to be sitting less than 8 feet away from a 60" set for your eyes to resolve full 1920x1080 in the first place, assuming that resolution is even there in the first place, which it normally isn't.

    A 1920x1080 set will display OTA at 1920x1080, and a 768 set will display it at 1366x768, so the difference in the V dimension is again exactly the same between sets as it was for DTV, and the difference between interpolating 1920 to 1280 and interpolating 1920 to 1366, the difference in the V dimension between sets, is very slim, and only for fully resolved images, which are rare.

    And none of that difference has anything at all to do with the amount of digital compression artifacts. That is an entirely different issue. If one set looks better than the other, you can rule out the amount of artifacts from the source content and you can all but rule out any reduced resolution. With different displays, there can be any number of other factors that could be creating a perceived difference, but I guess you can latch on to whatever superstitious theory you want to. You just won't have any proof or even acceptable theory to back it up.
     
  3. Jan 29, 2006 #83 of 118
    AbMagFab

    AbMagFab What happened, TiVo?

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    I appreciate the theory, but my eyes tell me something else. Take the specific example of OTA on my 1080p vs. the same content via DirecTV. OTA looks much much better. I'm not talking artifacts, I'm saying the picture looks better.

    When DirecTV reduces the resolution, they can't simply pluck out pixels, they need to do something to the picture to smooth out where they reduced the resolution. That means they are introducing stuff into the picture that wasn't there to begin with. And in doing so, they are making the picture look worse, much worse (IMO).

    I think I get your point, but it's not entirely true. The 1080p set (it's digital) upconverts everything to 1920x1080. But that's irrelevent since the HD Tivo (and any HD receiver) will have to upconvert it first (or at a minimum, convert it to a standard signal). So my TV is not showing a 1280x1080 picture, it's showing a 1920x1080 version of a 1280x1080 picture, and again, it looks much worse than the 1920x1080 equivelent (IMO).

    Math again. I am at around 8 feet from my 60". And it does look much much better. Eyes trump math theory.


    It's hardly superstition. DirecTV is reducing the resolution. In doing so, they have to do something to the picture so it still looks okay - smoothing it, whatever. In doing so, they are creating a picture that looks much worse, at least on a 1080p TV, than the original.

    It has nothing to do with compression artifacts, and I never said anything about artifacts.

    It has to do with picture quality, and the quality of the source, original, OTA picture compared with the DirecTV recompressed, reduced rez, messed with picture.

    And perhaps most importantly, FIOS isn't doing this at all - they are sending the full HD picture down, and they have substantially more HD (including locals). Cable also looks much better than DirecTV (although I can't compare on my TV, so it's not a fair comparison), and a better offering in my area.

    DirecTV is messing with their high-end customers. We care about picture quality (not math).
     
  4. Jan 29, 2006 #84 of 118
    bdlucas

    bdlucas Right side up again.

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    Can you say in what way the picture looks better? Sharper? Cleaner?

    One thing that might have been missed in this discussion is that in addition to downresing the image, which in itself will soften the image a little, DirectTV may be further softening the image in order to allow for compression to a lower bitrate while minimizing the artifacts. That is, sharpness can be traded off against artifacts in a compressor.

    As Ty has pointed out, the downresing that DirecTV is doing is probably not in itself enough to make a large difference in the quality of the image. Here's an illustration: the first image is the original, while in the second image I've simulated DirecTV's downresing (by downresing to 66% in the horizontal direction and then upresing to 150%). The difference is noticeable, but not enormous.

    [​IMG] [​IMG]

    Here's an illustration of the tradeoff of sharpness for artifacts at a given bitrate. Both of the following images have been compressed to 5K bytes. The first image is unprocessed before compression, while the second has been softened before compression (without changing the resolution). Result is a softer image but fewer artifacts. I wouldn't be surprised if DirecTV is doing something like this.

    [​IMG] [​IMG]

    In otherwords, I suspect TyroneShoes is right in that the downresing itself probably doesn't make a big difference in quality, and AbMagFab is right that DirecTV is degrading the quality of the picture in a way that becomes more noticeable on a higher-resolution screen.
     
  5. Jan 29, 2006 #85 of 118
    AbMagFab

    AbMagFab What happened, TiVo?

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    Perfect.

    The first set is very much like what I see when comparing OTA to DirecTV's version of the same thing. In fact, it's almost like the first picture = OTA, and the fourth picture is DirecTV's version. Yes, better than SD, but noticably worse (to me) than the same signal OTA.

    I guess detail is the word I would use. There's a noticable degredation in detail on DirecTV's HD.
     
  6. Jan 29, 2006 #86 of 118
    newsposter

    newsposter Poster of News

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    All this talk really makes me glad I only get 2 Hd stations on the satellite and the rest OTA.

    heck I'm even getting the very weak pbs station from philly now! (located actually in DE)

    and now I see nbc 10 apparently has chosen uhf 34..yippee

    http://www.fcc.gov/fcc-bin/tvq?list=0&facid=63153
     
  7. Jan 30, 2006 #87 of 118
    SpankyInChicago

    SpankyInChicago New Member

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    Totally subjective statement.

    Perhaps if you are taking a low-end, big-box RP-CRT for $1100 and comparing it to a $5000 SXRD.

    I had the choice between a $13,000 Qualia 006 and a $3500 Mitsubishi WS-65815. Both were within my budget. I had narrowed it down to a choice between these two after months of research. I think the Qualia 006 looked great. I will admit I had a hard time deciding which looked better. But the Qualia was not "much better" than the CRT. For film, I felt it was worse than the Mits. For sports, I felt it was better. Overall, all things considered, I still think the RP-CRT Mits looked overall better than the "top of the line" Qualia 006. That is what I went with and I saved $9,500.
     
  8. Jan 30, 2006 #88 of 118
    f300v10

    f300v10 New Member

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    I think I have read posts from your friends on the Atlanta area yahoo HDTV group. I have had no such issues since my install Dec. 10th. My D* HD locals are pretty much identical to the OTA versions 98% of the time. When the weather is bad I have seen some dropouts, but the rest of the time the D* locals look very good. The one exception seems to be football on CBS or NBC. The turf has some visible compression artifacts on the D* version that are not visible on the OTA version. ABC and Fox don't have that problem.
     
  9. Jan 30, 2006 #89 of 118
    AbMagFab

    AbMagFab What happened, TiVo?

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    Amazingly, 99% of people think the TV they bought is they best choice.

    Even if it wasn't, and even if much better choices are available now.
     
  10. Jan 31, 2006 #90 of 118
    SpankyInChicago

    SpankyInChicago New Member

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    Exactly. Because the "best" TV choice almost always depends on subjective observations. To say that one technology is "clearly" better than others with the state of TV technology today is to show ignorance of the subject. Of course, that may change in five years. But at this point, digital sets are not clearly better than CRT sets nor are CRT sets clearly better than digital sets.

    But I do understand that some people need to justify to themselves the fact that they were marketed into believing one technology was vastly superior to another.
     
  11. Jan 31, 2006 #91 of 118
    newsposter

    newsposter Poster of News

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    I'd add "at the price they wanted to pay for their current needs." I know darn well there are tons of better HD tvs out there but I wasn't ready to pay for them :)
     
  12. Jan 31, 2006 #92 of 118
    bdlucas

    bdlucas Right side up again.

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    Only those who are in denial about their buyer's remorse.
     
  13. Jan 31, 2006 #93 of 118
    AbMagFab

    AbMagFab What happened, TiVo?

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    Except my TV is better than your TV.
     
  14. Jan 31, 2006 #94 of 118
    Budget_HT

    Budget_HT Heavy User (of TiVo)

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    Okay children, let's be civil now.

    Everyone is entitled to their own opinion.

    Life would be boring if everyone agreed on everything.

    I have one of each type of TV (RPTV CRT and direct view LCD), and I see strengths and weaknesses in each. Oh, and I set up a DLP RPTV for a close relative, and even it has different attributes, some better and some worse.

    There is no single best here. Rankings are based on one's personal requirements, priorities and expectations.
     
  15. Feb 1, 2006 #95 of 118
    NoThru22

    NoThru22 Smelly Pirate Hooker

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    I still need to catch up with a lot that was said on page 3, but two things stood out to me so far:
    This is all going off the assumption that the mpeg2 and mpeg4 streams will be converted from the same source. I would assume that the mpeg4 stream will actually be derived from a decoded mpeg2 stream (I would more than assume actually, I'd put money on it) so by it's very nature the mpeg4 stream will always be inferior to the mpeg2 stream, even if only by a little (which, I will guess it will be more than a little and actually on the level of the current downrezzing.) This will not be like Blu-ray and HD-DVDs that will have direct mpeg4 transfers from the original source that will be gorgeous (if done properly.)
    I will refer you to my old quote: Ijustboughtcrapitis- the disease that makes a person delude themself into believing the crap they just bought is the best because they spent too much on it.
     
  16. Feb 1, 2006 #96 of 118
    newsposter

    newsposter Poster of News

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    another posting I've just run across and since a direct answer to the thread title, here it is:

    H20 Hard Reboot
    I upgraded last month to the H20 Mpeg4 set top box. I hooked up my OTA antenna and all the OTA local channels are great except for Fox , (2-1) in the local Detroit area. When I tune to the Fox OTA channel the H20 immediately goes into a hardware reboot. I am using the HDMI output to a Sony Ruby projector.

    Anyone have this problem and a solution?

    I use the OTA antenna because the quality of the local OTA broadcasts are substantially better than what D provides. Also was not informed at time of upgrade there was a 2 year commitment. And the hoops they make you go through just to apply for the $200 rebate combined with the fact that they rarely send it, has me rethinking why I am even doing business with these people. Thanks for any help you can provide.
     
  17. Feb 1, 2006 #97 of 118
    AbMagFab

    AbMagFab What happened, TiVo?

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    But you don't have a 1080p digital TV, so you can't compare.

    Your TV's are old and unfashionable.
     
  18. Feb 1, 2006 #98 of 118
    AbMagFab

    AbMagFab What happened, TiVo?

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    Sounds like the box is making a qualitative judgement on your programming choices. Like the FCC, the H20 is telling you what you can, and can't watch.

    Sounds like we finally have a 1-1 comparitive answer to the original poster. OTA is far greater quality than DirecTV MPEG-4. At least in Detroit.

    No surprise here. We've been saying it for 3+ pages...
     
  19. Feb 1, 2006 #99 of 118
    dswallow

    dswallow Save the ModeratŠ¾r TCF Club

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    I would advise against saying their TV's are unfashionable. ;)

    I was refrigerator shopping a few weeks ago and came across a modern version of that old-style Frigidaire look complete with the locking pull handle and rounded corners. $3999, too. A price premium for something that looked like it was from the 50's.

    It wasn't this one, but a simple search came up with it:

    [​IMG]

    It'll be amusing when someone creates a round HD plasma just to get that old fashioned round CRT look. :)
     
  20. Feb 1, 2006 #100 of 118
    NoThru22

    NoThru22 Smelly Pirate Hooker

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    This isn't the place for this discussion, but has it been proven that 1080p displays support 1:1 pixel mapping with deinterlaced 1080i signals? Over HDMI only then?
     

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